Internal combustion engines are well known to have properties and characteristics desirable for use as prime movers in various applications such as automotive and vehicular applications industrial machinery, and stationary power source applications. Several common configurations of the internal combustion engine include the turbine engine, for example, such as that found in the typical jet aircraft, the wankel-type engine, having a revolving piston, and occasionally found in automotive applications, and the reciprocating piston-type engine. The reciprocating piston-type internal combustion engine has been found to be adaptable and suitable for most common applications, including use in automobiles and trucks, industrial and construction machinery and as stationary power sources.
The reciprocating piston-type engine is typically found to operate in one of two thermodynamic cycles. The first is the Otto-cycle, typically burning a low-cetane fuel such as gasoline or kerosene, requiring an external system for spark-ignition of the fuel-air mixture in the engine to obtain combustion. The second is the Diesel-cycle in which combustion occurs spontaneously as a result of the compression of the fuel-air mixture. In practice, the lack of need for spark-ignition apparatus on the Diesel engine, coupled with the typically greater torque capability of the Diesel engine has rendered them suitable for use in those applications generally considered "heavy" or "rugged" duty, those being construction equipment, over-the-road trucks, railroad engines and agricultural equipment.
Additionally, reciprocating piston type Diesel engines have typically been physically larger and more massive than a comparable Otto-cycle engine, rendering the Diesel less suitable for applications where size and weight are primary considerations. This arises in part due to the nature of the respective cycles, in that the Diesel often operates at substantially higher compression ratios to obtain the compression required for ignition, with higher mechanical loads on the pistons, crankshaft and other components.
Other constraints are imposed by the size and timing of operation of the valves available to permit airflow into and out of the combustion chamber, the amount of compression available due to stroke length and bore diameter limitations in the typical piston assembly. For example, the common two-stroke engine provides one power stroke per crankshaft revolution, but has a limited ability to purge exhaust and charge the cylinder. On the other hand, the four stroke engine permits each cylinder to be purged of exhaust and fully charged prior to ignition, but can provide only one power stroke out of each two crankshaft revolutions. Additional external considerations, imposed in the form of concerns about particulate emissions, NOx emissions, and other pollutants, and costs of maintenance and operation, and manufacturability, often act as further limitations upon the performance of the typical reciprocating piston-type internal combustion engine.
Therefore, it is an object of the present invention to provide a dual compression and dual expansion engine which is simple to manufacture.
It is another object of the present invention to provide such a dual compression and dual expansion engine as may be readily manufactured by techniques and equipment consistent with those used in the manufacture of traditional reciprocating piston-type engines.
It is a further object of the present invention to provide such a dual compression and dual expansion engine as will have improved durability.
It is yet another object of the present invention to provide such a dual compression and dual expansion engine as may provide an improved power/weight ratio.
It is a further object of the present invention to provide such a dual compression and dual expansion engine as will be readily adaptable to use in those applications in which a traditional reciprocating piston diesel-type engine may be employed.
It is also an object of the present invention to provide such a dual compression and dual expansion engine as may suitably adapted for use in those applications in which the traditional Otto-cycle engine, such as the common reciprocating gasoline powered engine, may be employed.
It is yet a further object of the present invention to provide such a dual compression and dual expansion engine as will provide improved thermodynamic efficiency.
It is yet a further object of the present invention to provide such a dual compression and dual expansion engine as will provide improved control of pollutant emissions.
It is yet another object of the present invention to provide such dual compression and dual expansion engine as will be readily, simply, and inexpensively maintained.
These and other objectives of the present invention will become apparent in the specification and claims that follow.